Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/693—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with natural or synthetic rubber, or derivatives thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0041—Compositions of the carcass layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C9/0042—Reinforcements made of synthetic materials
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/73—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with carbon or compounds thereof
  • D06M11/74—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with carbon or compounds thereof with carbon or graphite; with carbides; with graphitic acids or their salts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C9/02—Carcasses
  • B60C9/04—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship
  • B60C2009/0416—Physical properties or dimensions of the carcass cords
  • B60C2009/0425—Diameters of the cords; Linear density thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C9/02—Carcasses
  • B60C9/04—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship
  • B60C2009/0475—Particular materials of the carcass cords
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/16—Dicarboxylic acids and dihydroxy compounds
  • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
  • C08G63/181—Acids containing aromatic rings
  • C08G63/183—Terephthalic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds

Definitions

• the present disclosure relates to a PET fiber-rubber composite and a tire.
• PET fibers In recent years, cords made from polyethylene terephthalate (PET) fibers have been primarily used as carcass materials for pneumatic tires. This is primarily because PET fibers exhibit superior balance in properties such as strength, modulus, and dimensional stability compared to conventional materials, such as nylon fibers and rayon fibers, and PET fibers are low-cost materials.
• PET fibers exhibit superior balance in properties such as strength, modulus, and dimensional stability compared to conventional materials, such as nylon fibers and rayon fibers, and PET fibers are low-cost materials.
• PET fibers have been unsatisfactory in terms of contribution to tire strength and weight reduction.
• cords that have even higher strength and contribute more significantly to weight reduction of tires.
• PET fiber-rubber composites with higher strength and lower rolling resistance has been pursued by replacing conventional PET fibers with PET fibers having an even higher strength.
• PET fiber-rubber composites As a technique to increase the strength of PET fiber-rubber composites, for example, the technique achieved by increasing the total fineness of PET fiber cords is known. However, although increasing the total fineness of the fibers can increase the strength, it also results in thicker cords, necessitating thicker PET fiber-rubber composites. This, in turn, negatively affects the rolling resistance when the PET fiber-rubber composites are applied to tires.
• PTL 1 discloses a method to reduce the hysteresis loss during driving by forming the cross-sectional shape of PET fiber cords closer to a perfect circle.
• a PET fiber-rubber composite of the present disclosure is a sheet-like PET fiber-rubber composite comprising PET fiber cords coated with a coating rubber,
• the above-described configuration can improve the strength and low rolling resistance characteristic when the PET fiber-rubber composite is applied to a tire, without incurring an increase in the total fineness of the cords or the thickness of the sheet.
• a tire of the present disclosure comprises the PET fiber-rubber composite of the present disclosure described above.
• the above-described configuration can achieve excellent strength and low rolling resistance characteristic.
• the present disclosure it is possible to provide a PET fiber-rubber composite that is excellent in strength and low rolling resistance characteristic when the PET fiber-rubber composite is applied to a tire, without incurring an increase in the total fineness of the cords or the thickness of the sheet. Furthermore, according to the present disclosure, it is possible to provide a tire that is excellent in durability and low rolling resistance characteristic.
• FIG. 1 is a diagram schematically illustrating a cross-section of a PET fiber-rubber composite according to one embodiment of the present disclosure.
• FIG. 1 schematically illustrates a cross-section of a PET fiber-rubber composite according to one embodiment of the present disclosure.
• the PET fiber-rubber composite of the present disclosure is a sheet-like PET fiber-rubber composite 100 including PET fiber cords 10 coated with a coating rubber 20.
• the PET fiber-rubber composite of the present disclosure satisfies the following formula (1): A / B / cord total fineness ⁇ 0.3
• a in the above formula (1) represents "the cord strength (N) ⁇ the fiber occupancy ratio".
• the fiber occupancy ratio in A is defined as "the cross-sectional area of a PET fiber cord (mm 2 ) / (the thickness of the PET fiber-rubber composite (mm) ⁇ (the diameter of a PET fiber cord (mm) + the inter-cord spacing of the PET fiber cords (mm)))".
• B in the above formula (1) represents the "rubber occupancy ratio”.
• the volume of rubber in the PET fiber-rubber composite is reduced, which contributes to weight reduction and the reduction in rolling resistance.
• the cord total fineness in the above formula (1) represents the sum of the finenesses of PET fibers 11. As this value increases, the thickness of the PET fiber 10 is increased, meaning higher strength but also increased mass.
• the PET fiber-rubber composite of the present disclosure preferably satisfies the following formula (1)': A / B / cord total fineness ⁇ 0.45
• the PET fiber cords are cords made of polyethylene terephthalate (PET) fibers and have an excellent balance of properties such as strength, modulus, dimensional stability, and manufacturing cost.
• PET polyethylene terephthalate
• the PET fiber cords may be single-twist cords or multi-twist cords each composed of two or more cords.
• the structure of the PET fiber cords can be appropriately selected according to the required performances of the PET fiber cords.
• the raw material for the PET fiber cords is not particularly limited and may be derived from synthetic products, may be derived from biological resources such as plant-based resources, animal-based resources, or microbial resources, may be obtained by mechanical recycling involving grinding, melting, and re-spinning resin products, or may be obtained by chemical recycling involving depolymerization and repolymerization of resin products, for example.
• the cord strength of the PET fiber cord is preferably 160 N or more, and more preferably 165 N or more, because the strength of the PET fiber-rubber composite can be further increased.
• the cord strength of the PET fiber cord can be appropriately controlled by adjusting, for example, the total fineness, the number of twists, and the raw yarn strength of the cord, and other factors.
• the raw yarn strength of a PET fiber constituting the PET fiber cord is preferably 7.8 cN/dtex or more, and more preferably 8.0 cN/dtex or more. Since this results in an increased strength of the PET fiber cord, the strength of the PET fiber-rubber composite can be further increased.
• the raw yarn strength of the PET fiber can be increased by adjusting the molecular weight, crystallinity, and crystal orientation of the PET resin, and other factors.
• the total fineness of the PET fiber cords is preferably from 1000 to 4800 dtex, and more preferably from 2000 to 4000 dtex.
• the strength of the PET fiber-rubber composite can be further increased.
• the total fineness of the PET fiber cords is 4800 dtex or less, it is possible to more reliably suppress the degradation of rolling resistance when the PET fiber-rubber composite is applied to a tire.
• the total fineness of the PET fiber cords refers to the sum of the finenesses of the PET fibers constituting the cords, and the total fineness can be controlled by adjusting the fineness and the number of twists of the PET fibers, and other factors.
• the diameter of a PET fiber cord is preferably 0.45 mm or more, and more preferably 0.50 mm or more. Furthermore, from the perspective of reducing rolling resistance, the diameter of a PET fiber cord is preferably 0.80 mm or less, and more preferably 0.70 mm or less.
• the fineness of the PET fibers is preferably from 550 to 2200 dtex, and more preferably from 1100 to 1670 dtex.
• the strength of the PET fiber-rubber composite can be further increased.
• the fineness of the PET fibers is 2200 dtex or less, it is possible to more reliably suppress the degradation of rolling resistance when the PET fiber-rubber composite is applied to a tire.
• the fineness of the PET fibers can be controlled by adjusting the type and manufacturing conditions of fibers, and other factors.
• the density of cords of the PET fiber cords is preferably 120 /10 cm or more, and more preferably 140 /10 cm or more, because the strength of the PET fiber-rubber composite can be further increased.
• the density of cords of the PET fiber cords refers to the number of PET fiber cords per 10 cm in the direction in which the cords are aligned in the PET fiber-rubber composite (in FIG. 1 , the density of cords corresponds to the number of PET fiber cords per 10 cm in the horizontal direction).
• the fiber occupancy rate in the PET fiber-rubber composite is not particularly limited as long as the above formula (1) is satisfied.
• the fiber occupancy rate is preferably 30% or more and 40% or less, and more preferably 35% or more and 40% or less.
• the fiber occupancy rate is determined as: the cross-sectional area of a PET fiber cord (mm 2 ) / (the thickness of the PET fiber-rubber composite (mm) ⁇ (the diameter of a PET fiber cord (mm) + the inter-cord spacing of the PET fiber cords (mm))).
• the diameter of a PET fiber cord refers to the diameter D of a PET fiber cord 10 that constitutes the PET fiber-rubber composite 100 in a cross-section, as illustrated in FIG. 1 .
• cross-sectional area of a PET fiber cord refers to the area S of the cross-section of a PET fiber cord 10 that constitutes the PET fiber-rubber composite 100, as illustrated in FIG. 1 .
• the inter-cord spacing of the PET fiber cords refers to the shortest distance P between adjacent cords 10 in the cross-section of the PET fiber cords 10 that constitute the PET fiber-rubber composite 100, as illustrated in FIG. 1 .
• the PET fiber cords are subjected to an adhesive treatment using an adhesive composition.
• the adhesive composition may include, for example, a thermoplastic polymer (A) having at least one pendant group with a crosslinkable functional group and substantially free of carbon-carbon double bonds with addition reactivity in the main chain structure thereof, a thermally reactive-type aqueous urethane resin (B), and an epoxy compound (C), and optionally further include a rubber latex (D).
• the adhesive treatment of PET fiber cords involves a so-called two-bath process in which epoxy or isocyanate is applied to the surfaces of the cords, followed by treatment with a resin formed by mixing resorcinol, formaldehyde, and latex (hereinafter referred to as RFL resin).
• RFL resin a resin formed by mixing resorcinol, formaldehyde, and latex
• the resin used in the first-stage bath can become extremely hard, increasing the strain input into the PET fiber cords, which can decrease the fatigue resistance of the cords.
• RFL resin can achieve sufficient adhesion between the cords and elastomer at room temperature, the adhesion may be reduced significantly at high temperatures of 130°C or higher.
• a single-stage bath mixture containing a thermoplastic polymer (A) having at least one pendant group with a crosslinkable functional group and substantially free of carbon-carbon double bonds with addition reactivity in the main chain structure thereof, a thermally reactive-type aqueous urethane resin (B), and an epoxy compound (C) can ensure sufficient adhesion with the elastomer (coating rubber) even at high temperatures of 180°C or higher without hardening the PET fiber cords.
• the main chain of the thermoplastic polymer (A) has primarily a linear structure, and the main chain is preferably an ethylene-based addition polymer such as an acrylic polymer, vinyl acetate-based polymer, and vinyl acetateethylene-based copolymer; an urethane-based high-molecular polymer; or the like, for example.
• the thermoplastic polymer (A) is not limited to the above-mentioned ethylene-based addition polymer or urethane-based high-molecular polymer, as long as it can inhibit flowability of the resin at high temperatures and ensure the rupture tenacity of the resin through crosslinking of the functional group on the pendant group.
• Preferred examples of the functional group on the pendant group of the thermoplastic polymer (A) include oxazoline groups, bismaleimide groups, (blocked) isocyanate groups, aziridine groups, carbodiimide groups, hydrazino groups, epoxy groups, and epithio groups.
• thermoplastic polymer (A), the thermally reactive-type aqueous urethane resin (B), the epoxy compound (C), and the rubber latex (D) described above that can be used may be those disclosed in JP 2023-040157 A or those disclosed in JP 2023-030762 A .
• a three-component mixture (adhesive composition) of the thermoplastic polymer (A), the thermally reactive-type aqueous urethane resin (B), and the epoxy compound (C) is preferably used as the treatment liquid for the first-stage bath, and a conventional RFL resin liquid is used as the treatment liquid for the secondstage bath.
• the proportion of the thermoplastic polymer (A) (dry mass ratio) is preferably 2 to 75%
• the proportion of the thermally reactive-type aqueous urethane resin (B) (dry mass ratio) is preferably 15 to 87%
• the proportion of the epoxy compound (C) (dry mass ratio) is preferably 11 to 70%
• the proportion of the rubber latex (D) (dry mass ratio) is preferably 20% or less.
• a dip treatment solution that does not contain resorcinol and formaldehyde as the adhesive composition for the PET fiber cords.
• An example of such a dip treatment solution is, for example, a composition containing a rubber latex (a) with an unsaturated diene and one or more compounds (b) selected from compounds containing a skeletal structure made of polyether and an amine functional group, compounds with an acrylamide structure, polypeptides, polylysine, and carbodiimides.
• an example of such a dip treatment solution is a composition containing, in addition to the above-described rubber latex (a) and compound (b), one or more selected from an aqueous compound (c) with a (thermally dissociative blocked) isocyanate group, a polyphenol (d), and a polyvalent metal salt (e).
• a composition containing polyphenols (I) and aldehydes (II) may also be used.
• Such a composition may further include at least one of an isocyanate compound (III) and a rubber latex (IV), in addition to the polyphenols (I) and the aldehydes (II).
• an adhesive composition to treat (coat) the PET fiber cords with adhesive contains the polyphenols (I) and the aldehydes (II), good adhesion can be achieved even when resorcinol is not used, considering environmental load.
• the adhesive composition includes the polyphenols (I) as a resin component
• the adhesion with the PET fiber cords can be enhanced.
• the polyphenols (I) are typically water-soluble polyphenols and are not particularly limited as long as they are polyphenols other than resorcinol (resorcinol).
• the number of aromatic rings or hydroxyl groups can be appropriately selected.
• the polyphenols (I) preferably have two or more hydroxyl groups, and more preferably have three or more hydroxyl groups.
• the polyphenols or the condensates thereof dissolve in the adhesive composition (dip treatment solution) containing water. Since this allows the polyphenols to be uniformly distributed in the adhesive composition, further excellent adhesion can be achieved.
• the polyphenols (I) are polyphenols containing two or more aromatic rings, each aromatic ring may have two or three hydroxyl groups located at the ortho, meta, or para positions.
• polyphenols (I) the polyphenol compounds disclosed in WO 2022/130879 A1 can be used, for example. These polyphenols (I) may be used alone or in combination of two or more.
• the adhesive composition includes the aldehydes (II) as a resin component in addition to the above-described polyphenols (I), high adhesion can be achieved in conjunction with the above-described polyphenols (I).
• the aldehydes (II) are not particularly limited and can be selected as appropriate depending on the required performances. It should be noted that in this specification, the aldehydes (II) encompass derivatives of aldehydes derived from aldehydes.
• aldehydes (II) examples include, for example, monoaldehydes such as formaldehyde, acetaldehyde, butyraldehyde, acrolein, propionaldehyde, chloral, butyraldehyde, caproaldehyde, and allyl aldehyde; aliphatic dialdehydes such as glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, and adipaldehyde; aldehydes containing an aromatic ring; and dialdehyde starch. These aldehydes (II) can be used alone or in combination of two or more.
• monoaldehydes such as formaldehyde, acetaldehyde, butyraldehyde, acrolein, propionaldehyde, chloral, butyraldehyde, caproaldehyde, and allyl aldehyde
• the aldehydes (II) are preferably aldehydes having an aromatic ring or contain aldehydes having an aromatic ring because they provide further excellent adhesion. Moreover, the aldehydes (II) are preferably free of formaldehyde.
• free of formaldehyde means, for example, that the formaldehyde content is less than 0.5 mass% of the total mass of the aldehydes.
• the polyphenols (I) and the aldehydes (II) are in a condensed state, and the mass ratio of aldehydes having an aromatic ring to polyphenols (the content of aldehydes having an aromatic ring/content of polyphenols) is 0.1 or more and 3 or less. This is because this ratio optimizes the hardness and adhesion of the resin formed as a condensation product of the polyphenols and the aldehydes having an aromatic ring.
• the mass ratio of polyphenols to aldehydes having an aromatic ring is more preferably 0.25 or more, and more preferably 2.5 or lower.
• the above-described mass ratio refers to the mass ratio based on the mass of the dried materials (solid content ratio).
• the total content of the polyphenols (I) and the aldehydes (II) in the adhesive composition is preferably 3 to 30 mass% because further excellent adhesion is ensured without compromising workability, etc. From a similar perspective, the total content of the polyphenols (I) and the aldehydes (II) in the adhesive composition is more preferably 5 mass% or more and more preferably 25 mass% or less.
• the above-described total content also refers to the total content based on the mass of the dried materials (solid content ratio).
• the adhesive composition preferably contains an isocyanate compound (III), in addition to the polyphenols (I) and the aldehydes (II) described above.
• the adhesion of the adhesive composition is further enhanced through the synergistic effect with the polyphenols (I) and the aldehydes (II).
• the isocyanate compound (III) is a compound that has an effect of promoting adhesion to the resin material, which is the adherend of the adhesive composition (e.g., phenol/aldehyde resin obtained through condensation of the polyphenols (I) and the aldehydes (II)), and is compound contains an isocyanate group as a polar functional group.
• the isocyanate compound (III) may be used alone or in combination of two or more.
• the isocyanate compound (III) is not particularly limited, but from the perspective of further improving adhesion, it preferably includes a (blocked) isocyanate group-containing aromatic compound.
• a (blocked) isocyanate group-containing aromatic compound in the adhesive composition results in the distribution of the (blocked) isocyanate group-containing aromatic compound near the interface between the PET fiber cords and the adhesive composition, thereby providing an effect of further promoting the adhesion. This effect allows the adhesive composition to achieve an even higher level of adhesion with the PET fiber cords.
• Examples of (blocked) isocyanate group-containing aromatic compounds that may be used include those described in JP 2023-040157 A and those described in JP 2023-030762 A .
• the content of the isocyanate compound (III) in the above-described adhesive composition is not particularly limited, but from the perspective of more reliably ensuring further excellent adhesion, the content is preferably 5 to 65 mass%. From a similar perspective, the content of the isocyanate compound (III) in the adhesive composition is more preferably 10 mass% or more and more preferably 45 mass% or less.
• the above-mentioned content is the content based on the mass of the dried materials (solid content ratio).
• the adhesive composition may substantially contain a rubber latex (IV), in addition to the polyphenol (I), the aldehydes (II), and the isocyanate compound (III) described above. This allows the adhesive composition to further enhance adhesion to rubber members.
• the rubber latex (IV) is not particularly limited and examples include, besides natural rubber (NR), synthetic rubbers such as polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR), or vinyl pyridine-styrene-butadiene copolymer rubber (Vp).
• NR natural rubber
• synthetic rubbers such as polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR), or vinyl pyridine-styrene-butadiene cop
• the content of the rubber latex (IV) in the adhesive composition is preferably 20 mass% or more, more preferably 25 mass% or more, and is preferably 70 mass% or less, and more preferably 60 mass% or less.
• the method for producing the adhesive composition is not particularly limited, but examples include, for example, a method of mixing and aging raw materials such as the polyphenols (I), the aldehydes (II), and the rubber latex (IV), or a method of mixing and aging the polyphenols (I) and the aldehydes (II) first, then adding the rubber latex (IV) followed by further aging.
• the method may include adding the rubber latex (IV), aging the mixture, and then adding the isocyanate compound (III).
• the coating rubber refers to the rubber that coats the PET fiber cords.
• the coating rubber is not particularly limited, other than defining the rubber occupancy rate of the coating rubber so as to satisfy the above formula (1).
• the composition and physical properties of the coating rubber may be appropriately selected according to the required performances.
• the coating rubber contains a rubber component containing 60 mass% or more of natural rubber and 40 mass% or less of non-oil extended styrene-butadiene rubber, and 30 to 60 parts by mass of carbon black with a nitrogen adsorption specific surface area (N 2 SA) of 60 m 2 /g or less per 100 parts by mass of the rubber component.
• N 2 SA nitrogen adsorption specific surface area
• the rubber component of the coating rubber preferably contains 60 mass% or more of natural rubber and 40 mass% or less of non-oil extended styrene-butadiene rubber.
• the inclusion of 60 mass% or more of natural rubber and 40 mass% or less of non-oil extended styrene-butadiene rubber can contribute to the low rolling resistance characteristic when the PET fiber-rubber composite is applied to a tire.
• the rubber component may also include various synthetic rubbers or nondiene rubbers, such as polyisoprene rubber (IR), polybutadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), isoprene-isobutylene copolymer rubber (IIR), ethylene-propylene-diene copolymer rubber (EPDM), halogenated butyl rubber (HR), and chloroprene rubber (CR), for example.
• various synthetic rubbers or nondiene rubbers such as polyisoprene rubber (IR), polybutadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), isoprene-isobutylene copolymer rubber (IIR), ethylene-propylene-diene copolymer rubber (EPDM), halogenated butyl rubber (HR), and chloroprene rubber (CR), for example.
• IR polyisoprene rubber
• BR polybutadiene rubber
• the coating rubber contains 30 to 60 parts by mass of carbon black with a nitrogen adsorption specific surface area (N 2 SA) of 60 m 2 /g or less, per 100 parts by mass of the rubber component.
• N 2 SA nitrogen adsorption specific surface area
• the N 2 SA of the carbon black is 45 m 2 /g or less.
• the strength of the PET fiber-rubber composite can be enhanced.
• the content of the content of carbon black By adjusting the content of the content of carbon black to 60 parts by mass or less per 100 parts by mass of the rubber component, it is possible to suppress the degradation of rolling resistance when the PET fiber-rubber composite is applied to a tire. From a similar perspective, it is more preferable that the content of carbon black is 35 to 45 parts by mass per 100 parts by mass of the rubber component.
• the coating rubber may appropriately include additives commonly used in the rubber industry, such as fillers (e.g., silica), vulcanizing agents, vulcanization accelerators, bismaleimide compounds, softeners, stearic acid, zinc oxide, resins, waxes, and oils, for example, as long as the effects of the present disclosure are not compromised.
• the inter-cord spacing P of the PET fiber cords is preferably 0.15 mm or more, and more preferably 0.17 mm or more, from the perspective of the durability of the tire upon high-speed driving. Additionally, from the perspective of maintaining the plunger energy, the inter-cord spacing P of the PET fiber cords is preferably 0.45 mm or less, and more preferably 0.40 mm or less.
• the PET fiber-rubber composite of the present disclosure is a sheet-like composite 100.
• the sheet-like composite is not particularly limited as long as the above formula (1) is satisfied.
• the tensile strength thereof is preferably more than 23,000 N/dm.
• the strength of the composite (N/dm) is calculated as the tensile tenacity of a single cord measured according to ASTM D885 multiplied by the number of cords per 10 cm width.
• the thickness of the sheet-like composite is preferably 1.8 mm or less, more preferably 1.5 mm or less, even more preferably 1.2 mm or less, and most preferably 1.0 mm or less.
• the PET fiber-rubber composite can be made lighter, thereby more reliably suppressing the degradation of rolling resistance when the composite is applied to a tire.
• the thickness of the sheet-like composite refers to the thickness T of the composite when it is cut along a plane perpendicular to the direction in which the cords extend in the composite, as illustrated in FIG. 1 .
• tan ⁇ of the coating rubber measured using a spectrometer manufactured by Kamishima Seisakusho Co., Ltd.
• a temperature of 24°C a strain of 1%
• a frequency of 52 Hz is 0.15 or less, more preferably 0.10 or less, from the perspective of reducing rolling resistance.
• tan ⁇ of the coating rubber mentioned in this specification refers to the value of tan ⁇ measured under the conditions of a temperature of 24°C, a strain of 1%, and a frequency of 52 Hz using a spectrometer (manufactured by Kamishima Seisakusho Co., Ltd.).
• the PET fiber-rubber composite of the present disclosure is required to satisfy the above formula (1), and preferably satisfies the above formula (1)'.
• the method for manufacturing the PET fiber-rubber composite of the present disclosure is not particularly limited and the PET fiber-rubber composite can be produced by known methods.
• the following method can be used, for example.
• a predetermined number of PET fiber cords are arranged in a reed screen-like shape.
• Unvulcanized rubber sheets that are made from the rubber composition and have a certain thickness are placed on both the top and bottom of the PET fiber cords so that the PET fiber cords are sandwiched by the unvulcanized rubber sheets. Thereafter, vulcanization is carried out at a temperature of approximately 160°C for about 20 minutes to obtain the PET fiber-rubber composite.
• the tire of the present disclosure includes the PET fiber-rubber composite of the present disclosure described above.
• the PET fiber-rubber composite of the present disclosure As a member forming the tire, excellent durability and low rolling resistance characteristic can be achieved.
• the site to which the PET fiber-rubber composite of the present disclosure is applied is not particularly limited.
• the PET fiber-rubber composite can be suitably used for a reinforcement member, such as a belt reinforcement layer, carcass ply, wire chafer, and other reinforcement members of various radial tires for automobiles.
• a reinforcement member such as a belt reinforcement layer, carcass ply, wire chafer, and other reinforcement members of various radial tires for automobiles.
• the PET fiber-rubber composite is preferably used for a belt reinforcement layer or carcass ply, and more preferably used for a carcass ply.
• the carcass ply is a member that constitutes the carcass, and the carcass may be composed of a single layer of carcass ply, or the carcass may be composed of two or more layers of carcass plies.
• the angle of the PET fiber cords may be substantially perpendicular to the tire circumferential direction, for example, the angle may be 80° to 90°.
• the locking structure of the carcass ply in the bead section is not limited to a structure where the carcass ply is wound around the bead core and locked.
• a structure in which the edge of the carcass ply is sandwiched between two layers of bead cores is also used.
• the tire of the present disclosure includes a belt layer.
• the belt layer may, for example, be composed of a first belt layer and a second belt layer laminated outward of the first belt layer in the tire radial direction.
• the first belt layer and the second belt layer are each composed of multiple cords embedded in the coating rubber.
• the thickness of the first belt layer and the thickness of the second belt layer at the tire center portion are each 1.00 mm or less.
• the ratio b/a is preferably 1.8 or more and 4.0 or less.
• This configuration ensures excellent durability at the belt edges while reducing rolling resistance.
• the thickness of each belt layer at the tire center portion is preferably 0.90 mm or less.
• the thickness of the second belt layer at the tire center portion is preferably 0.90 mm or less.
• the diameter of the cords embedded in the first belt layer and second belt layer and the thicknesses of the coating rubbers 5B and 6B are appropriately selected. It should be noted that the "tire center portion" refers to the region within one-quarter of the tire ground contact width from the tire equatorial plane, in the tire width direction.
• the reason for adjusting the value of the ratio b/a to 1.8 or more and 4.0 or less is that, by increasing the spacing between the cords in the first belt layer and the second belt layer at the belt edges, it is possible to suppress the strain that may cause belt edge separation.
• adjusting the value of b/a to 1.8 or more improves the durability at the belt edges, particularly the durability against belt edge separation.
• the value of b/a is preferably 1.95 or more, preferably 2.00 or more, and preferably 3.90 or less.
• the shortest distance b between the cord at the outermost end in the second belt layer and the cords in the first belt layer substantially refers to the shortest distance between the cord at the outermost end in the second belt layer and the tangent line of the multiple cords aligned in the first belt layer.
• the reinforcing fiber cords of the belt reinforcement layer may be appropriately selected.
• organic fiber cords with a breaking strength of 6.5 cN/dtex or more, an elongation at break of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN/(dtex ⁇ %) or more.
• Organic fiber cords with a breaking strength of 6.5 cN/dtex or more, an elongation at break of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN/(dtex ⁇ %) or more exhibit high strength at break, significant elongation at break, and high elastic modulus at 7% elongation.
• the breaking strength, elongation at break, and elastic modulus at 7% elongation of the organic fiber cords are those measured at room temperature (23°C).
• Various physical properties of the organic fiber cords can be measured in accordance with JIS L 1013 "Test Methods for Filament Yarns of Chemical Fibers.”
• the tire of the present disclosure is preferably a pneumatic tire.
• the gas to be filled in the pneumatic tire is normal air or air with adjusted oxygen partial pressure, as well as inert gases, such as nitrogen, argon, and helium, may be used.
• the method for manufacturing the tire of the present disclosure is not particularly limited and the tire can be manufactured based on conventional methods.
• a rubber composition containing various components is processed into members without being vulcanized, which are attached and shaped by conventional methods in a tire forming machine, to form a green tire.
• the green tire is then heated and pressurized in a vulcanizer to produce a tire.
• a rubber composition is obtained through kneading.
• the resulting rubber composition is used to apply rubber on PET fiber cords.
• An unvulcanized belt, unvulcanized carcass, and other unvulcanized members are laminated.
• the unvulcanized laminate is vulcanized to obtain a tire.
• a PET fiber-rubber composite for a carcass ply was prepared according to the conditions summarized in Table 1.
• PET fiber cords and a rubber composition summarized in Table 1 were used to obtain samples of PET fiber-rubber composite with the conditions listed in Table 1 (count of cords, inter-cord spacing, and composite gauge).
• the formulation of the rubber composition for the coating rubber that was coated, the conditions of the PET fiber cords (various physical properties and arrangement conditions), and the conditions of the composite (fiber occupancy rate, thickness, coating rubber occupancy rate, and tan ⁇ of coating rubber, A, B, and (A/B)/cord total fineness) for each sample are summarized in Table 1.
• the ply strength was calculated using the following formula based on the tenacity per one PET fiber cord measured according to ASTM D885 and the count of cords per unit. The results are summarized in Table 1. Higher values indicate greater ply strength.
• Ply strength (N/dm) tenacity per one PET fiber cord (N) ⁇ count of cords per unit (number/10 cm).
• a drum test was conducted in accordance with ISO 28580.
• the indices of the rolling resistance coefficients for the tires of Comparative Example 2 and Example 1 were calculated relative to the measured rolling resistance coefficient of the tire of Comparative Example 3 being set to 100.
• the results are summarized in Table 1.
• Example 2 the rolling resistance coefficient was predicted based on the test results of Comparative Example 2 and Example 1, as well as tan ⁇ and the volume ratio of the rubber.
• the results are also summarized in Table 1. Smaller index values indicate lower rolling resistance. It should be noted that the rolling resistance coefficient of the tire in Comparative Example 1 was not evaluated because the ply strength was low.
• the present disclosure it is possible to provide a PET fiber-rubber composite that is excellent in strength and low rolling resistance characteristic when the PET fiber-rubber composite is applied to a tire, without incurring an increase in the total fineness of the cords or the thickness of the sheet. Furthermore, according to the present disclosure, it is possible to provide a tire that is excellent in durability and low rolling resistance characteristic.

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• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• Tires In General (AREA)

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• 2023
  • 2023-09-15 CN CN202380068179.1A patent/CN119947903A/zh active Pending
  • 2023-09-15 JP JP2024550105A patent/JPWO2024070779A1/ja active Pending
  • 2023-09-15 WO PCT/JP2023/033783 patent/WO2024070779A1/ja not_active Ceased
  • 2023-09-15 EP EP23872007.2A patent/EP4596257A4/de active Pending

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